Dry Forest Research Articles

Managing fire‐prone forests in a time of decreasing carbon carrying capacity

Changing climatic conditions are increasing overstory tree mortality in forests globally. This restructuring of the distribution of biomass is making already flammable forests more combustible, posing a major challenge for managing the transition to a lower biomass state. In western US dry conifer forests, tree density resulting from over a century of fire‐exclusion practices has increased the risk of high‐severity wildfire and susceptibility to climate‐driven mortality. Reducing dead fuel loads will require new approaches to mitigate risk to the remaining live trees by preparing forests to withstand future wildfire. Here, we used data from the Teakettle Experimental Forest in California to evaluate different prescribed fire burn frequencies and their impact on accumulated dead fuels after a 4‐year drought. Increasing burn frequency could reduce surface fuel build‐up but comes with additional challenges that will require creativity and experimentation to overcome.

Does Bark Anatomy Influence the Selection of Woody Medicinal Plants in Seasonal Dry Forests from Brazil?

Does Bark Anatomy Influence the Selection of Woody Medicinal Plants in Seasonal Dry Forests from Brazil?

Tree architecture and leaf morphometry of Qualea grandiflora Mart. (Vochysiaceae) in a fragment of dry forest and pasture in the State of Goiás, Brazil

Investigating the functional traits of plant communities is extremely important for conserving habitats and plant species. This study aimed to evaluate the tree architecture and leaf morphometry of Qualea grandiflora (Vochysiaceae) in a fragment of semideciduous dry forest and pasture in the Boa Esperança settlement, municipality of Piracanjuba, State of Goiás, Brazil. Environmental, tree architecture, and foliar morphometry data were collected for seven trees in the semideciduous dry forest and five in the pasture area. We used the Shapiro-Wilk test to assess the normality of the collected data. The student t-test was used to compare the means of the functional traits between the two environments (forest and pasture). The average value of canopy cover was 85% for the semideciduous dry forest and 0% for the pasture. The mean values for leaf length and width were lower in the pasture. There was no significant difference in the petiole length in the two evaluated environments and for none of the functional traits related to the tree architecture. However, individuals of Qualea grandiflora grow better in the seasonal semideciduous dry forest, probably as a response to less stressful environmental conditions for this species. Thus, for sustainable exploitation by the local community, it is recommended that the tree matrices be chosen within the semideciduous dry forest area.

The role of local experts in the selection and use of fodder crop species: a case study in the Brazilian dry forest

The role of local experts in the selection and use of fodder crop species: a case study in the Brazilian dry forest

Comparative stem and wood anatomy of Ipomoea eriocarpa R.Br. (Convolvulaceae) growing in the arid zone and tropical deciduous forest

Family Convolvulaceae is dominated by climbing species and in most of the members, radial growth is achieved by forming vascular variants. The present study compares stem anatomy and structural modifications in the secondary xylem of Ipomoea eriocarpa R.Br. (Convolvulaceae) growing at Banni (Kachchh, arid zone) and at Toranmal (Tropical dry deciduous forest). Individuals growing at both biogeographic zones showed similar ontogeny for the development of successive cambia, inter-and intraxylary phloem, intraxylary cambium, and non-lignified axial (and radial) parenchyma wedges. However, as plants grew older, stems of individuals growing at Banni became lobbed in outline and showed the development of successive cambia and bidirectional intraxylary cambium. The thickest stems of samples from Banni possessed three successive cambial rings, vessels mostly solitary and relatively narrow in diameter with a greater number of non-lignified axial parenchyma wedges. In contrast, samples collected from Toranmal showed two successive cambial rings with relatively few numbers of non-lignified axial parenchyma wedges, intraxylary cambium was unifacial and exclusively produced intraxylary phloem. The secondary xylem was diffuse-porous, vessels usually in tangential multiples or clusters. Though, the time of seed germination and establishment of seedlings remained the same; in Banni samples, initiation of successive cambia, intraxylary cambium and its derivatives (i.e. xylem and phloem) began before the individuals growing at Toranmal. Samples from both locations showed the presence of inverse cambia on the inner margin of the xylem produced by the first successive cambium. These alterations in the behaviour may be correlated with the ephemeral lifecycle of Banni plants.

Leaf spectrum analysis of three tropical timber species: Diomate (Astronium graveolens), Choibá (Dipteryx oleifera), and Algarrobo (Hymenaea courbaril)

This study analyzed the leaf spectral response of three native timber forest species in the tropical dry forest: Diomate (Astronium graveolens Jacq.), Choibá (Dipteryx oleifera Benth.), and Algarrobo (Hymenaea courbaril L.). The study was conducted at the León Morales Soto Arboretum and Palmetum, at the Universidad Nacional de Colombia in Medellín, Antioquia, Colombia. Spectral data from the leaves were collected in situ using the portable spectroradiometer ASD FieldSpec HandHeld-2, which operates with a spectral resolution of 1 nm (resampled to 10 nm) and covers a spectral range between 325 and 1,075 nm (limited to 400-900 nm). Based on the measurements, the behavior and spectral variability of the species were evaluated. One-factor Analysis of Variance and Mann Whitney-Wilcoxon U-test were implemented in reflectance spectra to select the optimal narrow bands for species discrimination. The classification capacity of the selected narrow bands was assessed using the K-nearest neighbors’ algorithm. It was found that A. graveolens and H. courbaril exhibited spectral signatures typical of healthy vegetation, while D. oleifera showed spectral changes during the early stages of senescence. Regarding spectral separability, 23 narrow bands in the visible region and near-infrared region were identified as optimal for distinguishing the plant species. The supervised classification algorithm applied to these 23 narrow bands achieved an overall accuracy of 95.8%. In conclusion, these findings provide valuable insights into the spectral response of important tropical species and contribute to their conservation efforts by enhancing understanding of their unique spectral characteristics in diverse and heterogeneous ecosystems like tropical forests.

Different model assumptions about plant hydraulics and photosynthetic temperature acclimation yield diverging implications for tropical forest gross primary production under warming

AbstractTropical forest photosynthesis can decline at high temperatures due to (1) biochemical responses to increasing temperature and (2) stomatal responses to increasing vapor pressure deficit (VPD), which is associated with increasing temperature. It is challenging to disentangle the influence of these two mechanisms on photosynthesis in observations, because temperature and VPD are tightly correlated in tropical forests. Nonetheless, quantifying the relative strength of these two mechanisms is essential for understanding how tropical gross primary production (GPP) will respond to climate change, because increasing atmospheric CO2 concentration may partially offset VPD‐driven stomatal responses, but is not expected to mitigate the effects of temperature‐driven biochemical responses. We used two terrestrial biosphere models to quantify how physiological process assumptions (photosynthetic temperature acclimation and plant hydraulic stress) and functional traits (e.g., maximum xylem conductivity) influence the relative strength of modeled temperature versus VPD effects on light‐saturated GPP at an Amazonian forest site, a seasonally dry tropical forest site, and an experimental tropical forest mesocosm. By simulating idealized climate change scenarios, we quantified the divergence in GPP predictions under model configurations with stronger VPD effects compared with stronger direct temperature effects. Assumptions consistent with stronger direct temperature effects resulted in larger GPP declines under warming, while assumptions consistent with stronger VPD effects resulted in more resilient GPP under warming. Our findings underscore the importance of quantifying the role of direct temperature and indirect VPD effects for projecting the resilience of tropical forests in the future, and demonstrate that the relative strength of temperature versus VPD effects in models is highly sensitive to plant functional parameters and structural assumptions about photosynthetic temperature acclimation and plant hydraulics.

Influence of photosynthetic active radiation on sap flow dynamics across forest succession stages in Dinghushan subtropical forest ecosystem

With the intensification of global change, forests are subjected to varying degrees of drought or high-temperature stress, which has an indelible impact on the growth of trees. However, knowledge on the response of sap flow to environmental changes in different types of forests is still rare, especially in China's subtropical forest ecosystem. Consequently, studying how different tree species regulate their sap flow in response to shifting environmental conditions is essential for understanding forest transpiration, water use efficiency, and drought stress resilience. Therefore, this study aimed to investigate the sap flow dynamics of seven tree species in five forest plots, i.e., pine forest (PF), two types of mixed conifer-broadleaf forests (MF1+MF2), monsoon evergreen broadleaved forest (MEBF), and montane monsoonal evergreen broad-leaf forest (MOBF) at Dinghushan National Reserve in Southern China, using the heat dissipation probe technique and synchronous environmental factor recordings. Results demonstrated a significant influence of photosynthetic active radiation (PAR) on sap flow across all tree species, with mean PAR values ranging from over 1200 to 425 μmol m−2 s−1, establishing it as the principal driving factor. This observation underscores the heightened responsiveness or sensitivity of tree species to variations in PAR as the forest undergoes development and maturation. The correlation between vapor pressure deficit (VPD) and tree sap flow decreased as succession progressed. Moreover, the influence of soil water content (SWC) on sap flow stability against environmental changes increased. Similar patterns were also found between the two MF, with MF-2 displaying ecological characteristics and environmental conditions more closely aligned with those of the late-successional MEBF. The study reveals the intricate relationship between environmental factors and sap flow regulation in tree species within a subtropical forest ecosystem. Addressing a comparative gap in sap flow correlation among dominant tree species at Dinghushan, it establishes a hydro-physiological foundation for understanding tree species substitution during forest succession. The results provide key insights for forest management and climate-related research. Future studies should delve into the long-term implications of observed sap flow dynamics, exploring their impact on tree species adaptability amid ongoing environmental changes.

Opossums as opportunistic visitors of chiropterophilous flowers: Interaction between Didelphis albiventris (Marsupialia) and Hymenaea cangaceira (Fabaceae)

AbstractBat‐pollinated plants feature open flowers, facilitating easy access to their abundant nectar for various animal groups. The Caatinga, a Brazilian Seasonally Tropical Dry Forest, stands out globally as a hotspot for bat‐pollinated plants. This study presents the first documentation of the opossum Didelphis albiventris (Marsupialia) engaging in the consumption of nectar on flowers of Hymenaea cangaceira (Fabaceae), a bat‐pollinated tree species within the Caatinga. The observation spanned five nights and occurred unexpectedly during an experiment involving bagged flowers to assess nectar dynamics. Initially, torn bags were discovered containing flowers, which nectar had been consumed. Subsequent nights revealed the opossum actively exploring bagged flowers, likely guided by the fragrant nectar of H. cangaceira, and unmanipulated flowers located in the canopy's upper reaches. Given the opossum's contact with reproductive structures during these visits, it emerges as a potential pollinator. Following this observation, a comprehensive literature review on Didelphis interactions with other plants was conducted, leading to the construction of a meta network. This network unequivocally illustrates that the majority of plants visited by Didelphis indeed have bats as their primary pollinators. Owing to the nocturnal, arboreal and stealthy nature of opossums, documenting their interactions with flowers proves highly challenging. Consequently, our record highlights significant knowledge gaps in comprehending the interplay between opossums and chiropterophilous flowers. These gaps include the under‐sampling of this process in the Caatinga, the role of olfactory signalling and the broader consequences of this unique interaction.

A new addition to the toolbox: stone tool use in blonde capuchin monkeys (Sapajus flavius).

The use of tools played a central role in human culture and evolution. Early studies with apes demonstrated the tool use; however, currently the works have focused on Platyrrhine, particularly capuchin monkeys. Blonde capuchin monkeys, Sapajus flavius, have been observed using sticks to fish for termites in the Atlantic Forest, where this species has been extensively studied. In this study, we presented the first evidence of stone tool use by the blonde capuchin monkeys, as well as the dimensions and weight of these tools. We gathered data from three areas of Caatinga dry forest where we discovered this new tool use among the species. The mean weight of the hammers was 475.7g (± 142 SD). The mean height of the anvils was 48.3cm (± 18.7 SD), while the mean surface area of the anvils was 1.2 m2 (± 0.4 SD). We identified fruits and/ornuts from three plant species-Prunus dulces, Cnidoscolus quercifolius, and Syagrus coronate-near the anvils at the study sites. Additionally, we passively observed six instances of stone tool use by blonde capuchin monkeys. Their use of stones to crack encased foods mirrored behaviors previously reported in Sapajus libidinosus, a species well known for using stone tools to exploit hard nuts. Our findings place blonde capuchin monkeys among the list of primates that utilize stones as tools, highlighting the species' adaptability in exploiting resources within the Caatinga. Long-term studies are essentials to comprehend the use pattern of stone tools (across both general and seasonal perspectives) and the influence of variables, such as fruit hardness, distance to watercourses, and fruit availability on the use of this technology by this primate.

Inventatory of the funga in the Sierra de Cóndiro-Canales, Jalisco Mexico

The Sierra of Cóndiro-Canales is located between the municipalities of Atotonilco elAlto, La Barca and Ocotlán, which forms a polygon declared as a State HydrologicalProtection Area. Within this, three plant comunities are differentiated: deciduoustropical forest (BTC), oak forest (BE) and submontane scrub (MS). Fungi collectionswere carried out during the rainy season from 2021 to 2023, obtaining 123specimens, of which 85 were determined, corresponding to 60 species; of them, 52are Basidiomycota and eight are Ascomycota. Of the taxa collected, 29 from BE and31 are from the BTC and this is the vegetation with the greatest number ofdetermined species. Five new records are cited for the mycobiota of Jalisco:Lactarius uvidus, Paraisaria gracilioides, Peziza cerea, Phaeoclavulina flaccida andPluteus longistriatus.

Life history of the butterfly Phoebis argante (Fabricius, 1775) (Lepidoptera: Pieridae), an inhabitant of the dry forest of western Andes

Life history of the butterfly Phoebis argante (Fabricius, 1775) (Lepidoptera: Pieridae), an inhabitant of the dry forest of western Andes

Croton maranonensis: a new species of Euphorbiaceae from the tropical inter-Andean dry valleys

We describe Croton maranonensis Riina & Martín-Muñoz sp. nov., a species in Croton section Julocroton (Mart.) G.L.Webster from the seasonally dry tropical forests and shrublands of the inter-Andean valleys. This species is a small shrub occurring along the Marañón river valley in Peru and similar dry areas in southern Ecuador. We surveyed morpho-anatomical characters of the new species and closely related taxa. To confirm the placement of the new species in C. section Julocroton, we conducted a molecular phylogenetic analysis including three accessions of the new species and selected representatives of section Julocroton and related groups within Croton L. Micro- and macro-morphological evidence, and molecular data support C. maranonensis sp. nov. as an independent lineage within the C. section Julocroton clade. We compared the new species with morphologically similar species in the same section that also occur in the Andean region, including C. flavispicatus Rusby, C. triqueter Lam., and C. hondensis (H.Karst.) G.L.Webster.

Trees have similar growth responses to first-entry fires and reburns following long-term fire exclusion

Managing fire ignitions for resource benefit decreases fuel loads and reduces the risk of high-severity fire in fire-suppressed dry conifer forests. However, the reintroduction of low-severity wildfire can injure trees, which may decrease their growth after fire. Post-fire growth responses could change from first-entry fires to reburns, as first-entry fires reduce fuel loads and the vulnerability among trees to fire effects, which may result in trees sustaining less damage during reburns. To determine whether trees had growth responses that varied from first-entry fires to reburns, we cored 87 ponderosa pine trees in the Gila Wilderness, New Mexico, USA that experienced 3–5 fires between 1950 and 2012 following long-term fire-exclusion and 67 unburned control trees from the Gila and Apache-Sitgreaves National Forests. We assessed tree growth response to fire by comparing tree-ring growth among burned and unburned trees from two years before to two years after fires. We compared growth between burned and unburned trees using a bootstrapping procedure to calculate annual median tree-ring width index values with 95 % confidence intervals. We compared post-fire growth after first-entry fires and reburns following long-term fire-exclusion. Burned trees had similar growth responses following first-entry fires and reburns, with lower growth during the fire year through two years post-fire compared to unburned controls. Burned tree growth returned to expected rates following these immediate post-fire growth reductions. Interestingly, trees had lower growth during the year before and the year of reburns compared to the first-entry fire, reflecting greater aridity before reburns. Greater aridity may have contributed to larger-than-expected growth reductions following reburns, which could explain similar growth responses to first-entry fires and reburns. Our results indicate that trees had consistent short-term growth responses to low-severity fires following long-term fire-exclusion. As trees retained vigor after multiple fires, managing fires for resource benefit is an effective approach to reduce the likelihood of high-severity fire without long-term negative effects on tree growth.

Reconstructing the South American Miocene puzzle: An integrated analysis of the Paraná Formation (Argentina)

In recent decades, Miocene marine transgressions in South America have sparked ongoing debates concerning their boundaries, number of events, regional connectivity, and the existence of an epicontinental sea formed during the Andean orogeny. The bed-by-bed analysis of the Late Miocene Paraná Formation deposits in Entre Ríos Province (Argentina) allow defining six facies associations: (i) beach ridge, (ii) tidal inlet channel and washover fan, (iii) outer estuarine bioherms, (iv) central estuary, (v) tidal bar and sandflat, and (vi) tidal mudflat and creek deposits. Architectural and stacking pattern analyses reveal transgressive-regressive sequences typical of the coastal strip, encompassing shallow marine to estuarine sub-environments. The analysis identified diverse ecological guilds, including bivalve and gastropod assemblages in bioherms, and crustacean traces in tidal flats. Regressive units are characterized by wave-dominated shoreface deposits, while transgressive units comprise fine-grained estuarine deposits interbedded with bioclastic sandstones and storm deposits. The paleoenvironmental and paleoecological data indicate normal salinity marine environments with macroinvertebrates and estuarine components and suggesting tropical brackish conditions. Plant remains point to a range of vegetative communities, including mangroves, palm forests, grasslands, humid riparian forests, and dry upland forests, reflecting tropical to subtropical and humid to semiarid environments. This study concludes that the Paraná Formation correspond to a third-order transgressive system tract influenced by the Miocene Paranaense Sea. The basin-scale implications suggest that the distal Chaco-Paraná basin was affected by eustatic changes due to its low accommodation and topographic relief. The Chaco-Paraná foreland basin's evolution was driven by interactions between tectonic, climatic, and eustatic processes. The comprehensive analysis of sedimentary and fossil records provides a detailed paleogeographic reconstruction of the Miocene marine transgression in southern South America.

Is <i>Digitonthophagus gazella</i> undergoing a naturalization process? A study case in a tropical dry forest of northern Colombia

Is <i>Digitonthophagus gazella</i> undergoing a naturalization process? A study case in a tropical dry forest of northern Colombia

Ecotones as Windows into Organismal-to-Biome Scale Responses across Neotropical Forests.

Tropical forests are incredibly diverse in structure and function. Despite, or perhaps because of, this diversity, tropical biologists often conduct research exclusively in one or perhaps a few forest types. Rarely do we study the ecotone-the interstitial region between forest types. Ecotones are hyper-diverse, dynamic systems that control the flow of energy and organisms between adjacent ecosystems, with their locations determined by species' physiological limits. In this review, we describe how studying ecotones can provide key indicators for monitoring the state of Neotropical forests from organisms to ecosystems. We first describe how ecotones have been studied in the past and summarize our current understanding of tropical ecotones. Next, we provide three example lines of research focusing on the ecological and evolutionary dynamics of the ecotone between tropical dry forests and desert; between tropical dry and rainforests; and between Cerrado and Atlantic rainforests, with the latter being a particularly well-studied ecotone. Lastly, we outline methods and tools for studying ecotones that combine remote sensing, new statistical techniques, and field-based forest dynamics plot data, among others, for understanding these important systems.

Colubrina limae (Rhamnaceae), a new species from seasonally dry tropical forests of Brazil

Colubrina limae (Rhamnaceae, Ziziphoid group, subgen. Colubrina, sect. Cowania) is described and illustrated as a new species. We provide information on its geographical distribution, habitat, phenology, and conservation status. A table with key morphological characters comparing C. limae with all Brazilian species of Colubrina and one similar species in section Cowania is provided. C. limae differs remarkably from its congeners by the presence of stipitate glands on the abaxial side of leaves, brochidodromous venation, inflorescences in fascicles, and longer (>25 mm) fruit pedicels. It does have some morphological similarities with C. elliptica, a species from Central and northern South America. The new species is found mainly in the understory of seasonally dry forests associated with limestone outcrops; only two populations are recorded in the municipality of Januária in Minas Gerais state, Brazil.

Genetic structure and demographic history of the dung beetle Deltochilum guildingii (Scarabaeinae): implications for conservation of the Tropical Dry Forest in the Colombian caribbean

Genetic structure and demographic history of the dung beetle Deltochilum guildingii (Scarabaeinae): implications for conservation of the Tropical Dry Forest in the Colombian caribbean

A Phenomenon: What Are the Minuscule Grey Moths Abundant in the Dry Season in the Tropical Dry Forests of the Pacific Coast of Honduras?

Our investigation centered on the tropical dry forests along the Pacific coast of Honduras, aiming to elucidate the presence and abundance of minuscule grey moths during the dry season. Through specimen dissections and the taxonomic identification of the collected material, we have described three new species: Acalyptris podenasi sp. nov., A. palpiformis sp. nov., and A. tortoris sp. nov. Additionally, we documented two species previously known from neighboring countries, A. lascuevella Puplesis & Robinson and A. basicornis Remeikis & Stonis. The females of A. lascuevella were previously unknown and are documented here for the first time. Morphological examinations were complemented by DNA barcoding, particularly highlighting variation in A. lascuevella. The paper's primary significance lies not only in the description of new species but also in uncovering their taxonomic, morphological, and molecular importance. We found that these species are unique and indicative of the previously unstudied dry forests as a distinct ecosystem. Our findings revealed several novel atypical morphological traits within the studied Nepticulidae, including unusually large signum cells in the female genitalia, a dorso-ventrally divided uncus, and asymmetrical valvae in the male genitalia. These discoveries underscore the morphological diversity of Acalyptris Meyrick and their significance in evolutionary biology. Consequently, the paper addresses a previously unknown phenomenon of the occurrence and astonishing abundance of minuscule plant-mining micromoths in dry deciduous forests during the peak of the dry season. We hope that this paper will encourage Lepidoptera taxonomists to explore micromoths in other tropical dry forests, which, while limited in distribution, hold global importance. The paper is extensively illustrated with photographs of Acalyptris adults and their genitalia, along with maps, habitats, and molecular phylogenetic trees.